Abstract

DURING the course of disease transmission studies, it was found that certain stocks for long periods did not exhibit the characteristic symptoms of the disease, and were therefore believed to represent disease-resistant varieties. The leaf tissue from such operated and disease-resistant varieties was found non-infective as shown by transmission experiments conducted with the leaf on susceptible stocks. Two such plants on being accidentally injured—in one case by a borer, and by wind in the other, both involving the removal of much foliage—exhibited the characteristic symptoms during the course of 15 days after the accident, with sprouting of the dormant buds.